TARANIS

The satellite is intended to collect data on transient events that are observed during thunderstorms.[3] These events are happening between the medium and upper atmosphere, the ionosphere and the magnetosphere (radiation belts). The resulting phenomena in visible light are called Transient Luminous Events (TLE) and take a great diversity of forms (elves, halos, blue jets) varying in color, shape and duration. Thunderstorms are also known to generate gamma and X-ray photon emissions called Terrestrial Gamma-Ray Flashes (TGF), generated by intense electric fields in which the electrons are accelerated to the point of reaching energies up to 40 MeV (the bremsstrahlung process produces the photons). The link between TLEs and TGFs is one of the scientific questions of the TARANIS mission.[3] The Lightning-induced Electron Precipitations (LEP) will also be studied.[3] All these events have associated electromagnetic wave emissions that will be investigated as well.[3]

The Atmosphere-Space Interaction Monitor (ASIM) will operate as the same time as TARANIS and will provide complementary observations.

The TARANIS micro-satellite has a mass of 152 kg, and uses the Myriade platform powered by solar panels providing 85 watts. The amount of data transferred is planned to be 24 Gbits per day. The scientific payload is made of six instruments[4]

• MCP,[5] set of 2 cameras et de 3 photometers, 30 frames/s, 512 x 512 pixels and measuring the luminance in several spectral bands at high resolution;

• XGRE,[6][7] set of 3 detectors to measure high energy photons (20 keV to 10 MeV) and relativistic electrons (1 MeV to 10 MeV);

• IDEE,[8][7] set of 2 electron detectors to measure their spectrum between 70 keV to 4 MeV together with their pitch angle;

• IME-BF,[9] low frequency antenna to measure the electric field to a frequency up to 3.3 MHz;

• IME-HF,[10] high frequency antenna to measure the electric field at frequencies of 100 kHz to 30 MHz;

• IMM,[11] a tri-axis magnetometer of « search-coil » type to measure the magnetic field.

The studied phenomena last not more than a few milliseconds (except blue jets), therefore a specific recording method is implemented. Scientific instruments operate continuously and data is stored in a memory that is regularly purged of its oldest elements. If a phenomenon is noticed through one of the triggering instrument (XGRE, IDEE, MCP, IME-HF), the data of all the instruments corresponding to the period it took place is saved, and later transmitted to the ground.[6]

• French space program
• Guiana Space Centre